Support metadata files related to binary files

[dadoonet]

This is coming from this discussion: https://stackoverflow.com/a/76313247/1432281

We should support the indexation of specific metadata per file, by checking if a file named foo.pdf.json for example exists in a side folder with all the metadata files in it...

So we would define in the settings a new metadata_dir setting in which we would read the same virtual path and append .json.

So if we index a file named /path/to/relative/foo.pdf from the dir /path/to and have defined metadata_dir: /metadata where we have a file named /metadata/relative/foo.pdf.json, we will read that json content and merge it with the structure generated by FSCrawler.

That will offer a lot of flexibility for people who want to add information on each file. It could help to solve some user/group access information for example...

[nemo1991]

good idea.